1. Field of the Invention
The present invention relates to a container, and more particularly to an airtight storage container.
2. Description of the Related Art
Coffee beans are usually vacuum packed in tins or canisters for reducing the ability of the coffee beans to interact with oxygen and atmospheric moisture and thereby maintaining the beans fresh during an extended period of time prior to the use thereof. Once a consumer opens the vacuum packed container, the vacuum is lost. To further maintain fresh, the consumer may need to get a coffee canister for storing the coffee beans.
One type of canisters is shown in U.S. Pat. No. 1,621,132, in which there is shown a fruit jar cover for creating a partial vacuum in the jar by means of a hand pump and sealing an opening through which the air is withdrawn by a rubber cap. However, this type of canister is not suitable for storage of the coffee beans. It should be noted that the coffee beans themselves may ferment with time by nature and produce gas within the jar, causing an increase of pressure in the jar. Once the interior pressure is high enough to be greater than the outer atmospheric pressure, the rubber cap may no longer serve to seal the opening in the cover, and the cover may even further be lifted by the interior pressure, leading the coffee beans to interact with oxygen and atmospheric moisture undesirably.